Dear Darwin

Your letter has delighted me, & I want to answer it at length, which I shall do from Norwich where I go for 2 days on Friday. I now quite understand your Pangenesis—²

I wrote all the first half of my last letter by fits & starts, & no doubt made a precious muddle.³

It is all true what you say that the satisfaction which Pan. may give, will depend on mental constitution—or as I call it, Mental Parallax.—⁴

I never arrived at any such conclusion. nor did I ever in any way shape my thoughts or reason towards it because it was simply self evident.— What I have always instinctively held & thought & never could help seeing, is, that in all cases of descent, “all the properties of the parents are transmitted in the one cell”, (a wonder of wonders it always was & is to me.) & were diffused to every part of the future offspring—my examples being, the reproductive power of single cells of most lower orders of plants, of Bryum androgynum & many Ferns, & of Malaxis paludosa,⁵—on the one hand—, & the fertilized cell of all organisms on the other—

I do not see how any one who ever thought of the matter of descent could escape this conclusion—that the properties are not only transmitted by the one cell, but diffused thereafter throughout the future individual   It is so hard to conceive this, or rather to grasp this, for individuals; that when you come to extend it to species Genera—Orders classes &c. it may well form a stumbling block to the acceptation of the “Development of Species” doctrine—as it did with me.

So far I have instinctively held your doctrine—but never as a postulated or formulated theory or hypothesis— it was merely as part of the doctrine of descent, the most ordinary phenomena of descent being simply inconceivable to me without it— Much less did I ever ask myself whether the most obscure facts of reproduction were explicable on any other hypothesis.

So far we are agreed;— when you come to your atoms & germs & gemmules & so forth—we do not part company—but move off a little— I do not see my way— Tyndall⁶ believes he feels, atoms as firmly as S^t Paul believed he saw Christ.—⁷ I do not say that atoms do not exist; but I rather suppose that they maybe like minutes of time, or inches of space, or any other purely arbitrary quantities. Your doctrine of atoms thrown off in no way furthers my perceptions—or advances my ideas—

I have again read Part 1 of Pan, & with literally renewed delight. I do think Pan. as fine a thing as you ever writ.—the idea of germs & atoms notwithstanding—

As to laying claim to having by any logical process of reasoning arrived at such a doctrine, in any scientific sense i.e. by testing it as you have done—, do not for a moment entertain it— I always held, as part & parcel of the development doctrine, that the potentiality of the parent was not only transmitted by a cell, but indefinitely diffused therefrom—& hence, as I told you from the first, I could not see what there was new in your theory—except the idea of atoms &c. which I could not grasp.

My wife is laid up with a spraned foot or would go & see Mrs Darwin & you, as I hope to do next week⁸

Do dine with us at X Club on Thursday at 6 PM—⁹

Ev yr affec | J D Hooker